Inhibition of the dorsomedial striatal direct pathway is essential for the execution of action sequences.

Contrary to the previous notion that the dorsomedial striatum (DMS) is crucial for acquiring new learning, accumulated evidence has suggested that the DMS also plays a role in the execution of already learned action sequences. Here, we examined how the direct and indirect pathways in the DMS regulate action sequences using a task that requires animals to press a lever consecutively. Cell-type-specific bulk Ca recording revealed that the direct pathway was inhibited at the time of sequence execution.

Mesolimbic dopamine release precedes actively sought aversive stimuli in mice.

In some models, animals approach aversive stimuli more than those housed in an enriched environment. Here, we found that male mice in an impoverished and unstimulating (i.e.

Slow-rising and fast-falling dopaminergic dynamics jointly adjust negative prediction error in the ventral striatum.

The greater the reward expectations are, the more different the brain's physiological response will be. Although it is well-documented that better-than-expected outcomes are encoded quantitatively via midbrain dopaminergic (DA) activity, it has been less addressed experimentally whether worse-than-expected outcomes are expressed quantitatively as well. We show that larger reward expectations upon unexpected reward omissions are associated with the preceding slower rise and following larger decrease (DA dip) in the DA concentration at the ventral striatum of mice.

Minute-encoding neurons in hippocampal-striatal circuits.

Animals process temporal information in an ever-changing environment, but the neuronal mechanisms of this process, especially on timescales longer than seconds, remain unresolved. Here, we designed a hippocampus-dependent task in which rats prospectively increased their reward-seeking behavior over a duration of minutes. During this timing behavior, hippocampal and striatal neurons represented successive time points on the order of minutes by gradually changing their firing rates and transiently increasing their firing rates at specific time points.

Urethane anesthesia suppresses hippocampal subthreshold activity and neuronal synchronization.

Urethane, an anesthetic utilized for animal experiments, induces neocortical slow oscillations in which a large number of neurons emit rhythmic synchronized activity. However, it remains unclear how urethane affects neuronal activity in the hippocampus. In this study, we obtained in vivo patch-clamp recordings from dorsal hippocampal CA1 neurons in mice and found a reduction in the fluctuation of subthreshold membrane potentials during urethane anesthesia, implying reduced synaptic activity in the hippocampus.

Sniffing behaviour-related changes in cardiac and cortical activity in rats.

Key Points: High-frequency (HF) sniffing represents active odour sampling and an increase in the animal's motivation. We examined how HF sniffing affects the physiological activity of the brain-body system. During HF sniffing, heart rates and the ratio of theta to delta critical local field potential power were comparable to those observed during motion periods.

Vagus nerve spiking activity associated with locomotion and cortical arousal states in a freely moving rat.

The vagus nerve serves as a central pathway for communication between the central and peripheral organs. Despite traditional knowledge of vagus nerve functions, detailed neurophysiological dynamics of the vagus nerve in naïve behavior remain to be understood. In this study, we developed a new method to record spiking patterns from the cervical vagus nerve while simultaneously monitoring central and peripheral organ bioelectrical signals in a freely moving rat.

Simultaneous Recordings of Cortical Local Field Potentials, Electrocardiogram, Electromyogram, and Breathing Rhythm from a Freely Moving Rat.

Monitoring the physiological dynamics of the brain and peripheral tissues is necessary for addressing a number of questions about how the brain controls body functions and internal organ rhythms when animals are exposed to emotional challenges and changes in their living environments. In general experiments, signals from different organs, such as the brain and the heart, are recorded by independent recording systems that require multiple recording devices and different procedures for processing the data files. This study describes a new method that can simultaneously monitor electrical biosignals, including tens of local field potentials in multiple brain regions, electrocardiograms that represent the cardiac rhythm, electromyograms that represent awake/sleep-related muscle contraction, and breathing signals, in a freely moving rat.

Time-varying synchronous cell ensembles during consummatory periods correlate with variable numbers of place cell spikes.

Spike rates of a hippocampal place cell are not constant and vary even when an animal visits an identical place field with nearly identical behavior. As one potential neurophysiological source underlying place cell spiking variability, we focused on the temporally fluctuating activity states of neuronal ensembles. Spike patterns of hippocampal neurons were recorded from rats performing a linear track task.

Monitoring brain neuronal activity with manipulation of cardiac events in a freely moving rat.

Behavioral and cognitive studies have demonstrated that brain functions are affected by the activity states of the peripheral organs, such as the cardiac and respiratory systems. However, detailed neurophysiological mechanisms underlying the body-brain interactions remain unknown. In this study, we developed a method for manipulating activity levels of the heart using direct cardiac stimulation and vagus nerve stimulation that can be combined with recording cerebral local field potentials using a microdrive system, electrocardiograms, electromyograms, in a freely moving rat.

Hippocampal ripples down-regulate synapses.

The specific effects of sleep on synaptic plasticity remain unclear. We report that mouse hippocampal sharp-wave ripple oscillations serve as intrinsic events that trigger long-lasting synaptic depression. Silencing of sharp-wave ripples during slow-wave states prevented the spontaneous down-regulation of net synaptic weights and impaired the learning of new memories.

[Representation of Time by Hippocampal Neurons].

The hippocampus is involved in episodic memories of events including time and space. Many studies have focused on the neuronal processing mechanisms underlying spatial cognition and representation in the hippocampus; however, the time-related aspects of memories have only recently become the focus of research. In this review, we first introduce recent reports demonstrating the importance of the hippocampus in the perception of time and then present the hippocampal neuronal dynamics for the representation of time, revealed by large-scale neuronal recording techniques.

SNARE Molecules in Marchantia polymorpha: Unique and Conserved Features of the Membrane Fusion Machinery.

The membrane trafficking pathway has been diversified in a specific way for each eukaryotic lineage, probably to fulfill specific functions in the organisms. In green plants, comparative genomics has supported the possibility that terrestrialization and/or multicellularization could be associated with the elaboration and diversification of membrane trafficking pathways, which have been accomplished by an expansion of the numbers of genes required for machinery components of membrane trafficking, including soluble N-ethylmaleimide-sensitive factor attachment protein receptor (SNARE) proteins. However, information regarding membrane trafficking pathways in basal land plant lineages remains limited.